The death of a young cyclist in London, the tenth such fatality this year, is saddening news enough. The fact that it occurred at the wheels of an official Olympic shuttle bus, at a junction close to the Aquatics Centre described by cyclists as confusing and poorly signed, just adds to the tragedy – particularly for those of us that oppose the Games – as the sense of this being an avoidable and unnecessary death increases. Yet despite there being many ways to increase road safety for cyclists, something that is very drastically needed, conversation has – as is customary in Britain – shifted immediately and illiberally to criminalising cyclists that choose not to wear a helmet, a move rather bizarre as it is yet unclear whether the victim was or wasn't wearing such headgear. Olympic cyclist Bradley Wiggins suggested that laws should be changed, David Cameron, described it as a "difficult issue" and added – sitting awkwardly on the fence – that "There is a strong case for making them compulsory…there are some who take a different view. We should have a good look at this."

Such laws are of course well-intentioned. No sane person wants cyclists to be endangering their lives, and if someone in my family travelled by bike then I'd certainly want them to wear a helmet – estimated to reduce fatalities by 15 percent – though if I'm honest, and could ride a bike, and wanted to ride a bike, then I'd probably not. Yet once again we are at that situation where we must ask not just whether something is a good idea – wearing a helmet is a good idea in my opinion – but whether there are unintended consequences, and whether there is a genuine public interest at stake.

In terms of consequences, mandating cycling helmets in Australia has reduced cycling fatalities, but that's hardly surprising as cycling among Australians roughly halved as a result. Other research even calls into question whether helmets increase safety: as with other safety features our behaviour and that of others changes, making individuals less cautious, with motorists driving nearly 3 inches closer to helmet wearing cyclists than those without headgear. That's even before other actions that cannot be measured, such as general cautiousness, and factors such as speed, are fully considered. And as cycling charities have noted, reformers often demand legislation but then consider the problem fixed – believing in the magic absolute power of laws – focusing their attention elsewhere, never asking whether the law was the solution to the issue or just a distraction.

But the real issue here is not the consequences, or whether helmets are good or bad, but rather whether we should criminalise an activity that causes no harm to any other individual or wider society. Your decision to ride without headgear may be a bad idea, but by no stretch of the imagination can it be claimed to hurt anyone else. Over the past few decades governments have made more things illegal, made the punishments for breaking such laws more severe, and by doing so turned ever greater swathes of the public into law breakers, criminals, perpetrators of literally victimless crimes. If we criminalise cycling without a helmet we are making victimless acts criminal simply to express disapproval, without asking what the real human costs of enforcement are; if we fine cyclists flouting the law, and those cyclists refuse to pay that fine, are we willing to escalate the matter and prosecute, sending a cyclist to prison?

And more serious still is the dangerous precedent set. If we accept the logic behind cycling laws then we accept a logic in which government knows no bounds, no limits, no restriction, in which every activity by every individual within these shores is somehow the business of Whitehall. If we mandate cycling helmets then why not for drivers, as over half of car deaths are caused by head injury? Why not require pedestrians to wear high visibility jackets after sunset, cut the speed limit to 5mph, and have every vehicle employ a horseman to ride 10 yards ahead waving a red flag as a warning? People drown in bathtubs, should we ban bathtubs? Accepting cycling laws is to accept a logic of a nanny state tyranny. As CS Lewis warned us, "Of all tyrannies a tyranny sincerely exercised for the good of its victim may be the most oppressive. It may be better to live under robber barons than under omnipotent moral busybodies…those who torment us for our own good will torment us without end for they do so with the approval of their own conscience."

In short this legislative logic never ends; it cannot end, for if we regulate the individual for the individual's own sake then there is no distinction to be made between one activity and the next, no reasoning with which to draw a line in the sand. If self-endangerment is cause for control then every aspect of life is open for regulation, for as Harold MacMillan said "To be alive at all involves some risk".

In the end it comes down to the limits of the state and our individual liberty. The freedom not to wear a helmet may seem petty, trivial, reckless even, but rarely is freedom cast aside for tyranny in a single stroke of the legislator's pen; instead it is eroded, cut away at in a piecemeal fashion, chipped away grain by grain, each liberty deemed trivial, insignificant, of minor or no consequence. The freedom of speech boils down to individual words, the freedom of association comes down to individual meetings, and liberty itself comprises singular choices. We mustn't ever forget that.